Always fun to start with step 4 and work out.
I think some of the best questions would be based around gearing the wheels, or wheel size.
A) How does gearing affect speed/pushing power of a robot?
B) How does wheel size affect the speed/pushing?
C) How much weight can a ?? pound robot push? (does gearing affect that)
D) Surface: how does the surface affect item C?
Most of these will help her to better understand the robot, and will help with First LEGO League next year.
Hope that helps